He found it hard for Alan to focus on his teachers for longer than five minutes, _________ if the lecture was boring. 

It is commonly assumed that the growth of GDP and the development of people’s living conditions are not _______cause and effect.

— How do you find his new novel?    — His previous ones are great, and I think this one is _____ worth reading.

______ the agreement was reached without conflict.

The doctor thinks he will pull    now. His temperature has gone down.